This invention relates to projection-type kinescopes and particularly to a method for improving the spot size and phosphor linearity of projection kinescopes.
One type of projection television system uses three monochrome kinescopes, each having a cathodoluminescent screen with a different color emitting phosphor. The kinescopes project images through three lenses onto a reflective screen. The three different color images merge at the screen to form a composite color image.
The performance of such projection kinescopes is limited because of cathode current output limitations, space charge repulsion within the electron beams and nonlinearity of phosphor light output as a function of input electron beam energy. Because of the present low level of performance, the reflective screen in a projection system must be viewed in a darkened environment. Therefore, it is desirable to increase kinescope performance so that a projection kinescope may exhibit greater light output, thereby permitting the reflective screen to be viewed in greater ambient light or providing greater light output for theater viewing.